The administration of US President Barack Obama is reportedly reaching out to former Pakistani prime minister Nawaz Sharif as concerns mount over the survivability of the civilian government of his arch-rival President Asif Ali Zardari. American officials have long held Sharif at arm's length because of his close ties to Islamists in Pakistan, but some Obama administration officials now say those ties could be useful in helping Zardari's government to confront the stiffening challenge by Taleban insurgents, the New York Times reported. Sharif, who served as Pakistan's prime minister twice during the 1990s, represents the Pakistan Muslim League-N, which is supported by a number of Islamist groups. Quoting administration officials, the paper said Gen. David H. Petraeus, the head of the United States Central Command had said in recent private meeting in Washington that Pakistan's government is increasingly vulnerable. Gen. Petraeus is among those expected to attend an all-day meeting on Saturday with senior administration officials to discuss the next steps in Afghanistan and Pakistan, in advance of high-level sessions next week in Washington, when Zardari and President Hamid Karzai of Afghanistan will meet with President Obama at the White House. Obama administration officials have been up front in expressing dissatisfaction with the response shown by Zardari's government to increasing attacks by Taleban fighters and insurgents with Al-Qaeda in the country's tribal areas, and along its western border with Afghanistan. During a news conference on Wednesday, Obama said he was “gravely concerned” about the stability of the Pakistani government; on Friday, a Defense Department official described Zardari as “very, very weak.” The official told the New York Times that the administration wanted to broker an agreement not so much to buoy Zardari personally, but to accomplish what the administration believes Pakistan must do. “The idea here is to tie Sharif's popularity to things we think need to be done, like dealing with the militancy,” said the official, who insisted on anonymity to speak more candidly about American differences with Pakistan's government. Washington has a bad history of trying to engineer domestic Pakistani politics, and no one in the administration is trying to broker an actual power-sharing agreement between Zardari and Sharif, the paper said, citing administration officials. But the officials said that Secretary of State Hillary Rodham Clinton and Richard C. Holbrooke, the special representative for Afghanistan and Pakistan, have both urged Zardari and Sharif to look for ways to work together, seeking to capitalize on Sharif's appeal among the country's Islamist groups. Sir Mark Lyall Grant, director of political affairs at the British Foreign Office, was in Washington on Monday for talks with Holbrooke and Clinton on Pakistan, according to American and European officials. The three discussed Sharif, but no conclusions were reached, a European official said. “There's certainly no agreement that Nawaz should become Zardari's prime minister,” the official said, speaking on grounds of anonymity. He said the enmity between the two would make such a situation impossible. But he added: “We need people who have influence over the militancy in Pakistan to calm it down. Who's got influence? The army, yes. And Nawaz, yes.”